Project Description

Flood mitigation is high on the agenda of local and regional governments, as flood risk is increasing due to impacts of climate change on rainfall patterns as well as sea level rise. Tree planting has gained a lot of momentum for climate mitigation, as a method to quickly store atmospheric carbon. It is also often advocated as a method to mitigate flood risk – unfortunately, there is scarce evidence (Carrick et al., 2018) supporting it, leading to public agencies favouring engineered “grey” solutions instead.  

This project will be instrumental in providing evidence of an effect (or lack thereof) of tree planting for flood alleviation, in three environments: urban, peri-urban, and farmland, in and around the cities of Belfast and Aberdeen. In each context, trees will differ in species, density, age, and spatial configurations, with different impacts on water infiltration into soils, and flood runoff generation.  In urban and peri-urban settings, tree planting pits create “windows” of permeability in paved surfaces or compacted soils, and can be seen as regularly spaced water reservoirs, which can increase water infiltration potential regardless of tree species. That effect, and the additional effects of tree presence and local biodiversity will add-up or interact to further increase water infiltration: root water uptake for transpiration, evaporation of water intercepted by tree canopies, increasing soil water storage capacity, all potentially mitigate flood risks beneath trees. In larger woods and planted areas in peri-urban landscapes, these potential effects scale up further.   

Each site will be surveyed to measure tree canopy structure (Leaf Area Index etc.), soil infiltration capacity, tree root architecture using an in-house portable LiDAR (GeoSLAM), soil macrostructure, and soil invertebrate communities. These will help parameterise existing ecohydrological models, that will then be used to quantify water partitioning at the land surface and predict the likely spatio-temporal effects on flood generation at the different sites. Tree growth models will be used to predict short-term changes in canopy shading and tree root systems, to adjust predictions of flood models under different management scenarios. 

Possible project development includes policy science and work with stakeholders (Belfast and Aberdeen city councils, farmers, the Woodland Trust) to co-design tree planting strategies. 

Essential & desirable candidate skills

Essential: Enthusiasm, critical thinking and organisational skills. Background in environmental or geographical sciences. Familiarity with physical modelling / spatial / quantitative approaches. 

Desirable: Previous background in soil sciences, entomology, hydrological modelling, and field sampling are desirable but not essential. 


Paul Caplat

Primary Supervisor:

Profile: Paul Caplat
Institution: Queen's University, Belfast
Department/School: School of Biological Sciences

Chris Soulsby

Secondary Supervisor:

Profile: Chris Soulsby
Institution: University of Aberdeen
Department/School: School of Geosciences

Jennifer McKinley

Additional Supervisor:

Profile: Jennifer McKinley
Institution: Queen's University, Belfast
Department/School: School of Natural and Built Environment

Additional Supervisor:

Dr Carla Washbourne, UCL (policy science) 


Carrick, J, Abdul Rahim, MSAB, Adjei, C, et al. Is planting trees the solution to reducing flood risks? J Flood Risk Management. 2019; 12 (Suppl. 2):e12484. 

Research Methods

Fieldwork will be conducted in and around Belfast and Aberdeen, for two summers, with data analysis and modelling in between, translating the work into policy during the last year of the project (but co-design with stakeholders expected from the start). 


This project will be instrumental in getting evidence of an effect (or lack thereof) of tree planting for flood alleviation, using state-of-the-art methods in ecology and geosciences. Flood mitigation is high on the agenda of local governments, particularly in the context of sea level rise for coastal cities and farmland. Recent conflicts emerged in the choice of engineered infrastructure over Nature-Based Solutions in Belfast, leading to stakeholders (conservationists, Department for Infrastructure, City Council) thirsty for evidence. We aim to provide that evidence. We will address context dependence to increase generality and interpretation of outcomes, so that the results can be integrated in policy, with a section dedicated to that integration with help from Dr Washbourne at UCL and in collaboration with the City Councils and the Woodland Trust. 

Proposed Supervision

The project will be supervised in Belfast by Dr Paul Caplat (tree and landscape ecology, soil biodiversity; QUB), co-supervised by Dr Jenny McKinley (LiDAR, geostatistics; QUB), Prof Chris Soulsby (flood modelling, University of Aberdeen), and Dr Carla Washbourne (policy science, urban engineering, UCL). 

Proposed Timetable

  1. Literature review (October to December 2023) 
  2. Conceptual models and preparation of field survey (Jan to April 2024) 
  3. Belfast/Aberdeen surveys (soil cores, water infiltration, GeoSLAM) (May to August 2024) 
  4. Data analysis and modelling (September 2024 to April 2025) 
  5. Continue fieldwork in Belfast and Aberdeen (May to August 2025) 
  6. Continue data analysis and modelling (September 2025 to April 2026) 
  7. Horizon scanning and translation to planting guidelines (May 2026 to Dec 2026) 
  8. Write up (January to March 2027) 


  • biodiversity
  • earth-systems
  • environmental-management


CASE Partnerships with Belfast City Council and The Woodland Trust are currently under discussion. An update will be provided in due course.

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